1. Field of the Invention
The present invention relates to a conveyor device. More particularly, the present invention relates to a conveyor device that includes a branch path connected to a main conveyor and is configured to enable a person to perform sorting work by hand.
2. Description of the Related Art
A conveyor device is used to sort articles at a delivery center, a distribution base, or a factory. The conveyor device is, for example, a belt conveyor and includes a main conveyor (main line) and a plurality of branch paths (chutes) that branch from the main conveyor.
Articles are fed to the main conveyor and the articles are sorted to the different branch paths. One method of sorting is to use an automatic sorting machine. However, articles that are not suitable for the automatic sorting machine (i.e., articles that cannot be identified automatically because they are not compliant with a standard and articles comprising breakable items or valuable items that have been packaged) are sorted by hand. Hereinafter, such a conveyor device is called a hand sorting conveyor device.
More specifically, with a hand sorting conveyor device, a worker is stationed near a branch point of a branch path, and when an appropriate article is conveyed on the main conveyor, the worker moves the article to the branch path. In this way, articles are sorted to corresponding branch paths (e.g., see Japanese Laid-open Patent Publication No. 2006-36452).
A detector is provided on each of the branch paths. Each of the detectors is a photoelectric sensor or a limit switch. Types of photoelectric sensors that may be used are through-beam, mirror reflective, and diffuse reflective type sensors. When an article passes by the detector, the detector detects an on/off transition of a signal, and a control section counts the number of on/off transitions as the number of sorted articles. Counted numbers of articles are indicated on a sort count monitor provided on each of the branch paths. In this way, sorting performance management, progress management, and productivity management may be conducted.
However, with a conventional conveyor device, miscounts occur easily for reasons that will now be explained.
Firstly, if a worker moves a plurality of articles lumped together to a branch path, the number of articles counted by the detector will be smaller than the actual number of articles sorted.
Secondly, if the worker performs a movement that affects the detection of the detector (e.g., if the worker's hand blocks the light of the detector), the number of articles counted by the detector will be larger than the actual number of articles sorted.
Thirdly, if a branch becomes full or if an article jam occurs, such that articles become stagnant on the branch path, the detector will remain in an on-state. Thus, the detector cannot detect an article properly.